Uneven layers

Veti

at 800mm it would be easy to have one axis offset by a millimetre. that could cause binding of the lead screws.
the ingus nuts are very thight for those lead scews.

Haggan90

This is how it looks right now.

deckingman

@haggan90 If those screws are constrained at the top, try taking the upper mount off. The linear guides should be contstraining any XY movement, not the screws. So if you allow the top of the screws to "float" it will ensure that there are no binding issues.

Haggan90

@deckingman they are Only constraint at the top and not at bottom. I got a flec coupling on the steppers at the bottom.

deckingman

@haggan90 said in Uneven layers:

@deckingman they are Only constraint at the top and not at bottom. I got a flec coupling on the steppers at the bottom.

Those flex couplings might be the cause of your problems, depending on what type they are. If you have any sort of binding on the bearings, some designs of the flex couplings can "wind up" absorbing some of the movement. Then a bit more tension is enough to overcome the binding and you get a sudden jump.

Haggan90

@deckingman That makes sense... because when I attach a precision gauge to the bed and move it down it only moves around 0.001mm-0.003 so it's sturdy. Would any sort of printed couplings work?

Haggan90

@deckingman I just tried to push the couplings together as hard as I could to see if it makes any diffrence, will be back with a photo!

Haggan90

@deckingman Dammit, made no diffrence at all =(

antlestxp

i just upgraded a back up printer I have to a maestro and that printer now shows the same banding. is there a possibility of a firmware issue with coarse threaded z rods. I use fine pitch rods on my primary printer and don't have the issue. or at least it isn't obvious on that printer. they are both hypercubes with the only difference being the pitch of the threaded rods.

this part was printed at .2 in petg with the latest fw
M350 X16 Y16 Z16 E16 I1
M92 X80.00 Y80.00 Z800.00 E407.16

antlestxp

8bit with octoprint vs maestro on the same printer. I will admit 2 different brands of abs and re-sliced to account for the different fw flavor.

Haggan90

@antlestxp looks exactly like my problem!

Haggan90

I tried with a more challanging print and got the same results.

dc42

@antlestxp said in Uneven layers:

8bit with octoprint vs maestro on the same printer. I will admit 2 different brands of abs and re-sliced to account for the different fw flavor.

Did you slice using the exact same layer height in both?
Have you run heater tuning on the bed heater? If you haven't, then it will run in bang-bang mode, which often contributes to layer banding.
Are you using the same Z motor current in both cases?
What stepper drivers does your 8-bit board use? If they don't support stealthChop, or it doesn't use them in stealthChop mode, then it's possible that the default low-speed stealthChop mode of the drivers on the Maestro could be reducing the Z axis precision. So try configuring the Z drivers not to use stealthChop (see the M569 command).

HTH David

Haggan90

@dc42 In my case it's as follow:

Yes exactly the same slicer settings in all cases.
No bed heater installed yet.
N.A
Is this something that I should try? I'm using a Duet Wifi with an Duex2.

Also I just tried with diffrent microstepping and with/without interpolotion. Same results.
Tried with flexible couplings and with stiff couplings on the steppers as well, same result.

I'm comming back to that this could be a firmware or config issue, but I'm out of ideas =/

Veti

what do you mean n/a for question 3?

Haggan90

@veti Dave was replying to @antlestxp as he had changed from an 8 bit controller to the duet maestro. I have only used the duetwifi in all examples

antlestxp

@dc42

yes same slicer settings with the exception of relative vs absolute extrusion.
i used bang-bang on 8bit and PID on the maestro
same current on both (the maestro runs so much cooler, pretty happy about that)
Trinamic 2130 (had a love hate relationship with them)

I will get some single perimeter prints going with and without stealthchop and see what happens.

antlestxp

@haggan90 I don't think it is a mechanical problem. we are using 2 different printers and see the same issue. My peaks are exactly 4mm apart. Looking at a print a while back with the bad bearing I see that the bulges looked like they were the same distance but they actually weren't. Also where they started were different every print. Yesterday I printed several different models of different shapes and sizes and they all start at the same spot. I even removed and reinstalled the z leads and it looks like they are still in the same position.

dc42

@antlestxp said in Uneven layers:

My peaks are exactly 4mm apart.

I presume you mean the horizontal bands have peaks 4mm apart in the Z direction.

What is the pitch of the Z leadscrew on your printer?
Do you have 1 Z motor or 2? If 2, how are they connected to the Duet, and what is the model number of the motor(s)?

antlestxp

The bulges match the pitch. The lead screws are 2mm pitch 2 start. There are 2 screws and 2 motors connected one to each connector on the duet. I will have to dig up the model of the motors but I know for sure they are 1.8 degree 40Ncm.